Climate Change

Climate change is one of the greatest threats to human civilisation, but determining future climate scenarios can only be built on the foundation of what we know has happened before. From understanding the variability in Earth’s climate and the possible mechanisms which drive global climate cycles, scientists have been able to develop highly sophisticated models of our future climate and are delivering crucial information to the public and government about the possible consequences of anthropogenic activity.

Stable isotope analysis works as a virtual paleo-thermometer, allowing readings of past earth temperatures in a variety of materials such as micro-fossils, ice cores and tree rings. By combining this temperature information and extrapolating into the future, we maybe able to avoid the worst outcomes and stable isotope analysis will play a crucial role in helping us do this.

Carbonate Materials

Climate signals are found throughout the seabed in the form of sedimented carbonate materials from ancient biota. The 13C and 18O isotope ratios of these materials a directly related to the ocean temperature at the time of their existence. Our Dual Inlet inlet system equipped the MultiCarb is capable of the highest precision 13C and 18O analysis of extremely small samples, as well as offering exciting new "clumped isotope" analysis.

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Ice core water analysis

The isotopic ratio of precipitation is fundamentally dependent on the temperature of the oceans it evaporates from. Ice cores from the arctic and antarctic polar regions have been recording the isotope variation for millennia making it possible to determine the temperature at the time that the ice was laid down. Our AquaPrep is able to perform the highest 18O and 2H analysis compared to any other technique, reducing uncertainty in your temperature proxy calculations.

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Greenhouse Gases

Greenhouse gases in the atmosphere are major drivers for climate change. Decoupling the anthropogenic contribution of these gases to the atmosphere from those that are the result of natural processes is vital if we are to understand the mechanisms for climate change. Using iso FLOW, you can investigate the isotopic ratios of the main greenhouse gases CO2, N2O and CH4 in atmospheric gas samples to help develop strategies to cope with climate change.

Climate change publications using our instruments

Our customers use our instruments to do some amazing research in the climate change application field. To show you how they perform their research and how they use our IRMS instruments, we have collected a range of peer-reviewed publications which cite our products. You can find the citations below and then follow the links to the publishing journal should you wish to download the publication.

If you would like to investigate our available citations in more detail, or email the citation list to yourself or your colleagues then take a look at our full citation database.

A high-resolution temporal record of environmental changes in the Eastern Caribbean (Guadeloupe) from 40 to 10 ka BPQuaternary Science Reviews (2017)

In neotropical regions, fossil bat guano accumulated over time as laminated layers in caves, hence providing a high-resolution temporal record of terrestrial environmental changes. Additionally, cave settings have the property to preserve such organic sediments from processes triggered by winds (deflation, abrasion and sandblasting) and intense rainfall (leaching away). This study reports both stable carbon and nitrogen isotope compositions of frugivorous bat guano deposited in a well-preserved stratigraphic succession of Blanchard Cave on Marie-Galante, Guadeloupe. These isotopic data are discussed with regard to climate changes and its specific impact on Eastern Caribbean vegetation during the Late Pleistocene from 40 to 10 ka cal. BP. Guano δ13C values are higher than modern ones, suggesting noticeable vegetation changes. This provides also evidence for overall drier environmental conditions during the Pleistocene compared to today. Meanwhile, within this generally drier climate, shifts between wetter and drier conditions can be observed. Large temporal amplitudes in both δ13C and δ15N variations reaching up to 5.9‰ and 16.8‰, respectively, also indicate these oceanic tropical environments have been highly sensitive to regional or global climatic forcing. Stable isotope compositions of bat guano deposited from 40 to 35 ka BP, the Last Glacial Maximum and the Younger-Dryas reveal relatively wet environmental conditions whereas, at least from the end of the Heinrich event 1 and the Bølling period the region experienced drier environmental conditions. Nevertheless, when considering uncertainties in the model age, the isotopic record of Blanchard Cave show relatively similar variations with known proxy records from the northern South America and Central America, suggesting thus that the Blanchard Cave record is a robust proxy of past ITCZ migration. Teleconnections through global atmospheric pattern suggest that islands of the eastern Caribbean Basin could be also under the influence of a bipolar temperature gradients that impact the mean location of the ITCZ, with a Southern Hemisphere imprint during the glacial period and a more significant role of Northern Hemisphere during the last deglaciation.

During the Aptian Oceanic Anoxic Event 1a, about 120 million years ago, black shales were deposited in all the main ocean basins1. The event was also associated with elevated sea surface temperatures2, 3 and a calcification crisis in calcareous nannoplankton4. These environmental changes have been attributed to variations in atmospheric CO2 concentrations2, 3, 5, 6, but the evolution of the carbon cycle during this event is poorly constrained. Here we present records of atmospheric CO2 concentrations across Oceanic Anoxic Event 1a derived from bulk and compound-specific δ13C from marine rock outcrops in southern Spain and Tunisia. We find that CO2 concentrations doubled in two steps during the oceanic anoxic event and remained above background values for approximately 1.5–2 million years before declining. The rise of CO2 concentrations occurred over several tens to hundreds of thousand years, and thus was unlikely to have resulted in any prolonged surface ocean acidification, suggesting that CO2 emissions were not the primary cause of the nannoplankton calcification crisis. We find that the period of elevated CO2 concentrations coincides with a shift in the oceanic osmium-isotope inventory7 associated with emplacement of the Ontong Java Plateau flood basalts, and conclude that sustained volcanic outgassing was the primary source of carbon dioxide during Oceanic Anoxic Event 1a.

Marginal Calluna populations are more resistant to climate change, but not under high-nitrogen loadsPlant Ecology (2016)

The dominant plant species of European heathlands Calluna vulgaris is considered vulnerable to drought and enhanced nitrogen (N) loads. However, impacts may vary across the distribution range of Calluna heathlands. We tested the hypothesis that Calluna of southern and eastern marginal populations (MP) are more resistant to drought events than plants of central populations (CP), and that this is mainly due to trait differences such as biomass allocation patterns. Furthermore, we hypothesised that N fertilisation can offset differences in drought susceptibility between CP and MP. We conducted a full-factorial 2-year greenhouse experiment with Calluna plants of CP and MP and quantified growth responses in terms of biomass production, allocation and tissue δ13C signatures. Biomass production, shoot–root ratios and tissue δ13C values of 1-year-old plants were higher for CP than for MP, indicating a higher drought susceptibility of CP. These trait differences were not observed for 2-year-old plants. N fertilisation increased shoot–root ratios of 1- and 2-year-old plants and across populations due to a stimulation of the aboveground biomass allocation. As a consequence, population-related differences in drought susceptibility were offset for N-fertilised plants. We concluded that Calluna plants originating from different populations developed adaptive traits to local climates, which determined their drought sensitivity. However, the higher drought resistance of MP can be attenuated by an N-induced increase in shoot–root ratios. This suggests that analyses on plant growth responses to global change should include multi-factor approaches with a focus on different populations throughout a species’ distribution range.

We put forward a general conceptual model of CO2 behaviour in the vadose zone of karst aquifers, based on physical principles of air flow through porous media and caves, combined with a geochemical interpretation of cave monitoring data. This ‘Gibraltar model’ links fluxes of water, air and carbon through the soil with the porosity of the vadose zone, the circulation of ground air and the ventilation of caves. Gibraltar hosts many natural caves whose locations span the full length and vertical range of the Rock. We report results of an 8-year monitoring study of carbon in soil organic matter and bedrock carbonate, dissolved inorganic carbon in vadose waters, and gaseous CO2 in soil, cave and ground air. Results show that the regime of cave air CO2 results from the interaction of cave ventilation with a reservoir of CO2-enriched ground air held within the smaller voids of the bedrock. The pCO2 of ground air, and of vadose waters that have been in close contact with it, are determined by multiple factors that include recharge patterns, vegetation productivity and root respiration, and conversion of organic matter to CO2 within the soil, the epikarst and the whole vadose zone. Mathematical modelling and field observations show that ground air is subject to a density-driven circulation that reverses seasonally, as the difference between surface and underground temperatures reverses in sign. The Gibraltar model suggests that cave air pCO2 is not directly related to CO2 generated in the soil or the epikarstic zone, as is often assumed. Ground air CO2 formed by the decay of organic matter (OM) washed down into the deeper unsaturated zone is an important additional source of pCO2. In Gibraltar the addition of OM-derived CO2 is the dominant control on the pCO2 of ground air and the Ca-hardness of waters within the deep vadose zone. The seasonal regime of CO2 in cave air depends on the position of a cave in relation to the density-driven ground air circulation pattern which is itself determined by the topography, as well as by the high-permeability conduits for air movement provided by caves themselves. In the steep topography of Gibraltar, caves in the lower part of the Rock act as outflow conduits for descending ground air in summer, and so have higher pCO2 in that season. Caves in the upper Rock have high pCO2 in winter, when they act as outflow conduits for rising currents of CO2-enriched ground air. Understanding seasonal flows of ground air in the vadose zone, together with the origins and seasonal regimes of CO2 in cave air underpins robust interpretation of speleothem-based climate proxy records.

Seasonal δ13C and δ18O data are presented from 14 Unio sub-fossil shells unearthed at the archaeological site of Çatalhöyük in central Turkey, spanning the occupation period ca. 9150–8000 cal years BP. The shells likely lived in the small lakes/wetlands around the site before being gathered and taken to Çatalhöyük. Wet-dry seasonal cycles are clearly apparent in the δ18Oshell profiles with low winter values reflecting winter precipitation and high δ18O in the summer resulting from evaporation. The most striking trend in the δ18O data is the drop in maximum summer δ18O ca. 8300 years BP, which we infer as indicating lower summer evaporation and hence a reduction in seasonality. Previous palaeoclimate records from the area have suggested cooler and more arid conditions, with reduced precipitation, around this time. While the drop in summer δ18O values could be due to reduced summer temperatures reducing summer evaporation, but there was little change in winter δ18O, perhaps suggesting winter growth cessatio...

The carbon isotope and sequence stratigraphic record of the Sheinwoodian and lower Homerian stages (Silurian) of the Midland Platform, UKPalaeogeography, Palaeoclimatology, Palaeoecology (2016)

Helen E. Hughes, David C. Ray

New high resolution δ13Ccarb isotope data are presented through the Sheinwoodian and lower Homerian stages of the Wenlock Series (Silurian) from sections in Shropshire, Herefordshire and the West Midlands (UK). This data identifies the well-known Early Sheinwoodian positive Carbon Isotope Excursion (ESCIE), the minor mid-ESCIE negative shift, and an Early Homerian positive Carbon Isotope Excursion (EHCIE) in the region of 1.4‰, as developed upon the Midland Platform and in close proximity to the Sheinwoodian and Homerian GSSPs. These carbon isotope excursions have been correlated against graptolite, conodont and chitinozoan frameworks from across the Midland Platform, and alongside details of sedimentology and faunas, have allowed for the establishment of a sequence stratigraphic framework. These integrated data sets reveal that the shallow-water Barr–Buildwas–Woolhope limestones reflect approximately synchronous deposition across the Midland Platform; in that they all contain the ESCIE and five widely traceable depositional cycles. Moreover, biostratigraphic and sequence stratigraphic frameworks from across the Midland Platform (Avalonia) confirm that both the ESCIE and the five cycles are synchronous with records from other palaeocontinents (Baltica and Laurentia) and indicate that the early Sheinwoodian graptolite zones as established in the type area are in need of review.

Oxygen isotope compositions of tooth enamel increments in theropod dinosaurs are investigated as potential proxies of climate seasonality. Six teeth of large carnivorous theropods collected from four Cretaceous formations deposited under contrasted climates have been sampled. These teeth have been analyzed for the oxygen isotope compositions of their apatite phosphate ({delta}18Op) through incremental sampling performed along the major growth axis. Significant fluctuations in oxygen isotope compositions along the growth axis of each tooth are observed and interpreted as reflecting seasonality in ingested local surface water {delta}18Ow values. Fluctuations in {delta}18Op values of theropod teeth from the Aptian of Thailand and Cenomanian of Morocco vary similarly to meteoric water {delta}18Omw values occurring today in sub-tropical regions subjected to large seasonal amounts of precipitations. A dinosaur tooth recovered from the more inland and mid-latitude Nemegt Formation of Mongolia shows a seasonal pattern similar to present-day cold temperate and continental climate. Finally, the high latitude and coastal Kakanaut Formation (Russia) experienced strongly dampened seasonal variations, most likely due to the influence of warm Pacific oceanic currents. Such conditions occur today in high latitude regions submitted to marine influence. These results further highlight the potential of using the oxygen isotope compositions of large theropod teeth to reconstruct past seasonal variations of terrestrial climates. Increased knowledge of past seasonality may help to better understand the complex interactions between climate and the dynamics of land biodiversity in terms of ecological adaptations, biogeography and the evolutionary history of organisms.

Seasonality fluctuations recorded in fossil bivalves during the early Pleistocene: Implications for climate changePalaeogeography, Palaeoclimatology, Palaeoecology (2016)

Understanding the transformations of the climate system may help to predict and reduce the effects of global climate change. The geological record provides a unique archive that documents the long-term fluctuations of environmental variables, such as seasonal change. Here, we investigate how seasonal variation in seawater temperatures varied in the Mediterranean Sea during the early Pleistocene, approaching the Early-Middle Pleistocene Transition (EMPT) and the beginning of precession-driven Quaternary-style glacial–interglacial cycles. We performed whole-shell and sclerochemical stable isotope analyses (δ18O, δ13C) on bivalves, collected from the lower Pleistocene Arda River marine succession (northern Italy), after checking shell preservation. Our results indicate that seawater temperature seasonality was the main variable of climate change in the Mediterranean area during the early Pleistocene, with the Northern Hemisphere Glaciation (NHG) exerting a control on the Mediterranean climate. We show that strong seasonality (14.4–16.0°C range) and low winter paleotemperatures (0.8–1.6°C) were likely the triggers leading to the establishment of widespread populations of so called “northern guests” (i.e., cold water taxa) in the Mediterranean Sea around 1.80Ma. The shells postdating the arrival of the “northern guests” record a return to lower seasonal variations and higher seawater paleotemperatures, with seasonality increasing again approaching the EMPT; the latter, however, is not associated with a corresponding cooling of mean seawater paleotemperatures, showing that the observed seasonality variation represents a clear signal of progressive climate change in the Mediterranean Sea.

Tabon Cave is a key site for the understanding of modern human dispersals in the Philippine archipelago and Island Southeast Asia. Nestled in the karst landscape that borders the southwestern coast of Palawan, it has delivered the earliest confirmed Homo sapiens remains in the Philippines dating to the late Pleistocene, as far back as around 47 ka. Among other methods, the broad characteristics of the environment in which these humans once lived may be drawn using stable isotope analysis of the rich guano deposits in the cave, an approach that follows a growing number of studies indicating the potential of guano as a palaeoenvironmental archive. δ13C values reveal the general prevalence of C3 forest tempered by savannah woodland with grassland contributions both well before and slightly after a securely-dated fireplace at 32 ka; the lower interval would refer to OIS 3 or older interglacial periods, while the upper interval would refer to the transition either before or after the Last Glacial Maximum. No useful conclusions are drawn from δ15N results due to suspected ammonia fractionation. Pending future dating efforts for confirmation, this preliminary study contributes to the development of an alternative and promising palaeoenvironmental proxy and hopes to shed further light on the prehistoric odysseys that took place across Island Southeast Asia.

Inseok Chae, Jungjae Park

We present a multi-proxy record (pollen, microscopic charcoal, carbon-isotopic composition [δ13C], organic content, and particle size) of the late-Holocene climate change and human impact from central-eastern South Korea. The Medieval Climate Anomaly (MCA) and Little Ice Age (LIA), the most recent major climate events, have not been accurately investigated by paleolimnological studies in Korea, mainly due to a lack of undisturbed sediments and indifference to the past climate change. Our pollen records show late- Holocene centennial climate variations characterized by the successive solar minimums of the Oort, Wolf, Spörer, Maunder, and Dalton. We find paleoenvironmental evidence for shifting cultivation associated with serious droughts and consequent famines during the early 19th-century Dalton minimum. Our interpretation of human activities is well supported by Korean historical documents describing socioeconomic suffering induced by LIA climate deteriorations.

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